The present invention generally relates to valve assemblies for internal combustion engines. More particularly, the present invention relates to a rotary valve system for multi-cylinder internal combustion engines which allows a cross-flow of gasses therethrough.
An operating cycle of an internal combustion engine, as is well known in the art, consists of four phases in the 4-stroke Otto cycle corresponding to respective piston strokes. These four stages comprise an intake phase for the aspiration of an explosive air/fuel mixture, a compression and ignition phase, an expansion or power phase, and an exhaust phase.
Internal combustion engines traditionally employ poppet type valves which require valve operating trains including valve springs, a camshaft, etc., in order to convert the rotary motion of the engine into the linear movement required by the poppet valves. These poppet valves are normally opened by movement mechanically inwardly of a cylinder in which they are placed by means of a rocker arm actuated by a push rod which in turn has been actuated by hydraulic lifters or the like driven from a camshaft in synchronism with the operation of the engine. Valve return has usually been by spring means. While a cam in head engine eliminates the push rods that are otherwise required, the cam mechanism does include levers and springs for maintaining the valves in a closed position.
Conventional poppet valves have various problems associated with them. A conventional poppet valve engine requires considerable power to overcome the resistance to opening the valves against cylinder pressure. The application of the necessary power to open the valves produces wear in the valve train. Further, the members of the valve train are reciprocating, resulting in power being dissipated while overcoming the inertia of the members in changing direction. Such valve structure also requires additional hood height and is inefficient at high speeds. Further, since the valves in the train are constantly exposed to the high temperature of the ignited fuel in the cylinders, burning of the valves at sustained high speed operation is possible.
Engines incorporating rotary valves have proven superior in certain respects in that they can be made with larger valve openings and are not limited by restrictions imposed by camshaft configurations, such as the necessary rise and fall times of the poppet valve operating cams. Also, such rotary valve engines are basically simpler in that they eliminate the need for valve operating trains.
The concept of a rotary valve in internal combustion engines has been present for many years. Although there is still high interest in rotary valves, no rotary valve engines have been incorporated into automobiles produced by the large automobile manufacturers. This is due, in part, to the fact that most of the previous designs were not able to be operably implemented into the engine. Some designs require entirely new engine and supporting system designs to accommodate the rotary valve system. Other designs have been found to be either impractical or excessively expensive.
Accordingly, there is a need for a rotary valve head system which can replace a traditional poppet type valve operating train without requiring significant alterations to the remainder of the engine. What is also needed is a rotary valve head system which is operable with standard engines while being cost effectively manufactured and implemented. The present invention fulfills these needs and provides other related advantages.
The present invention resides in a rotary valve head system for a multi-cylinder engine having pistons residing within multiple cylinders capable of reciprocal movement to form multiple combustion chambers. The system includes a hollow intake rotary valve tube having closed ends and multiple apertures corresponding to each cylinder intake port. Each aperture is registerable with an engine intake means, such as a conventional intake manifold, and a cylinder intake port according to an intake timing mechanism operably linked to the intake rotary valve tube. Similarly, a hollow exhaust rotary valve tube has closed ends and multiple apertures corresponding to each cylinder exhaust port. Each aperture is registerable with an engine exhaust means, such as a conventional exhaust manifold, and a cylinder exhaust port according to an exhaust timing mechanism operably linked to the exhaust rotary valve tube.
A cylinder head overlies the multiple cylinders and the intake and exhaust rotary valve tubes. The cylinder head has head intake ports registered with the cylinder intake ports of the multiple cylinders and registerable with the apertures of the intake rotary valve tube. Likewise, the head includes exhaust ports registered with the cylinder exhaust ports of the multiple cylinders and registerable with the apertures of the exhaust rotary valve tube.
The intake and exhaust rotary valve tubes may be generally cylindrical. At least one bushing overlies a portion of an outer surface of each of the intake and exhaust rotary valve tubes. Alternatively, the intake and exhaust rotary valve tubes includes spherical components having apertures aligned with the intake and exhaust rotary valve tube apertures. Bushings overlie the intake and exhaust rotary valve tubes between the spherical components.
The cylinder head is configured such that a clearance is provided between the cylinder head and outer surfaces of the intake and exhaust rotary valve tubes. A sleeve can be interposed between either the intake rotary valve tube or the exhaust rotary valve tube and the cylinder head. The sleeve has apertures aligned with the head intake or exhaust ports and cylinder intake or exhaust ports and registerable with the apertures of the intake or exhaust rotary valve tube. Sealing inserts are positioned within the cylinder head at the cylinder intake and exhaust ports. Means are provided for maintaining contact between the inserts and the intake and exhaust rotary valve tubes to form an air-tight seal between the intake and exhaust rotary valve tube apertures and the cylinder head.
Typically, a rod extends from an end of each of the intake and exhaust rotary valve tubes for connection to a bearing assembly secured to the cylinder head. The intake timing mechanism is operably linked to the rod extending from the intake rotary valve tube, and the exhaust timing mechanism is operably linked to the rod extending from the exhaust rotary valve tube.
Incoming air/fuel from the intake means is admitted within an aperture of the intake rotary valve tube and permitted to flow through the hollow intake rotary valve tube until entering into a cylinder through a tube aperture registered with a head intake port and cylinder intake port. The outgoing combustion products are emitted through an aligned cylinder exhaust port, head exhaust port, and an aperture of the exhaust rotary valve tube and permitted to flow through the hollow exhaust rotary valve tube until exiting into the exhaust passage means through an exhaust rotary valve tube aperture which is registered with the exhaust passageway means.
Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.